Packing bag

ABSTRACT

To provide a packing bag, with which waste refuse is not generated, used in good appearance after opening, the bag is composed of a rectangular sheet piece  1  of synthetic resin, the sheet piece  1  is folded on two convex folded line portions  18  and a concave folded line portion to form a folded portion  10  serially having a first sheet layer  11,  a second sheet layer  12,  a third sheet layer  13,  and a fourth sheet layer  14  on an end edge portion  1 A to form M-shape in longitudinal cross section; the first sheet layer  1  and the second sheet layer  2  are fused, and the third sheet layer  3  and the fourth sheet layer  4  are fused; a separation-prepared line portion  5  to separate the second sheet layer  2  and the third sheet layer is formed along the concave folded line portion  19  between the second sheet layer  2  and the third sheet layer  3;  a fastener  4  to mutually seal the second sheet layer  2  and the third sheet layer  3  is provided; and the separation-prepared line portion  5  is disposed on an inner side of the bag to the fastener  4.

FIELD OF THE INVENTION

This invention relates to a packing bag.

BACKGROUND ART

Conventionally, a packing bag, provided with a fastener on an opening predetermined portion, is proposed to be used with seal after opening (refer to patent document 1, for example)

In the packing bag of the patent document 1, a fastener is attached to an inner side of a sheet piece having obverse and reverse sides, a peripheral edge portion is welded to be sealed for the entire periphery before opened, an opening portion is formed by cutting a part of the peripheral edge portion along a cutting line formed above the fastener, and the opening portion can be opened and closed by using the fastener.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Provisional Publication NO. 2006-290424.

OUTLINE OF THE INVENTION Problems to be Solved by the Invention

However, in the packing bag of the patent document 1, the cut face frequently becomes non-straight because a part of the peripheral edge portion is ripped by hands when opened, and the appearance is bad when used with seal by the fastener. And, the cut piece of the peripheral edge portion becomes refuse, and useless waste is generated.

Therefore, it is an object of the present invention to provide a packing bag which does not generate useless refuse, and can be used with good appearance after the opening.

Means for Solving the Problems

The packing bag relating to the present invention is a packing bag composed of a rectangular sheet piece of synthetic resin, the sheet piece is folded on two convex folded line portions and a concave folded line portion to form a folded portion serially having a first sheet layer, a second sheet layer, a third sheet layer, and a fourth sheet layer on an end edge portion to form M-shape in longitudinal cross section, the first sheet layer and the second sheet layer are fused, and the third sheet layer and the fourth sheet layer are fused, a separation-prepared line portion to separate the second sheet layer and the third sheet layer along the concave folded line portion between the second sheet layer and the third sheet layer, a fastener to mutually seal the second sheet layer and the third sheet layer, and the separation-prepared line portion is disposed on an inner side of the bag to the fastener.

And, left and right both end edge portions of the sheet piece are welded in a state that the folded portion is formed on the end edge portion, and an opening portion to put a packed article in the bag is formed on another end edge portion.

And, a slider is attached to the folded portion to open and close the fastener.

And, a through hole for suspension is formed on the folded portion.

Effects of the Invention

According to packing bag of the present invention, the bag can be opened by breaking the sheet piece on the separation-prepared line without cutting the peripheral edge portion, and used in good appearance after the opening. And, refuse is not generated because the bag can be opened not cutting the peripheral edge portion. The strength on the end edge portion composed of the folded portion is secured, the fastener can be easily opened and closed, and the bag is appropriate for suspended display. In spite of the construction with the fastener, the bag can be produced with low cost. The sheet piece can be continuously printed in the form of rolled sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A front view showing an embodiment of the present invention.

FIG. 2 A longitudinal cross-sectional view showing the packing bag of FIG. 1.

FIG. 3 A cross-sectional view of a principal portion showing a state just before opening.

FIG. 4 A cross-sectional view of the principal portion showing a state just after opening.

FIG. 5 A front view showing another embodiment of the present invention.

FIG. 6 A longitudinal cross-sectional view showing the packing bag of FIG. 5.

FIG. 7 A front view showing still another embodiment of the present invention.

FIG. 8 Perspective views to explain production method of the packing bag in which: (A) is a perspective view showing a first process and a second process; (B) is an enlarged perspective view showing a chuck tape male portion and a chuck tape female portion; and (C) is an enlarged cross-sectional view of a sheet material.

FIG. 9 An enlarged cross-sectional view of the second process to explain the production method of the packing bag.

FIG. 10 A perspective view of the third process to explain the production method of the packing bag.

FIG. 11 An enlarged cross-sectional view showing a state of the sheet material before the third process of the production method of the packing bag.

FIG. 12 An enlarged cross-sectional view showing a state of the sheet material after the third process of the production method of the packing bag.

FIG. 13 A perspective view of the fourth process to explain the production method of the packing bag.

FIG. 14 An enlarged cross-sectional view of the fourth process to explain the production method of the packing bag.

FIG. 15 An enlarged cross-sectional view showing a state of the sheet material after the fourth process of the production method of the packing bag.

FIG. 16 A perspective view of the fifth process to explain the production method of the packing bag.

FIG. 17 A cross-sectional view of a principal portion of the fifth process to explain the production method of the packing bag.

FIG. 18 A perspective view of the sixth process to explain the production method of the packing bag.

FIG. 19 A perspective view of the seventh process to explain the production method of the packing bag.

FIG. 20 A top view of a used state to explain an indicating portion.

FIG. 21 An enlarged cross-sectional view of a principal portion.

FIG. 22 A perspective view showing another production method.

FIG. 23 A front view of the packing bag produced by another production method.

FIG. 24 A perspective view showing still another production method.

FIG. 25 A perspective view showing a further production method.

EMBODIMENTS OF THE INVENTION

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.

As shown in FIG. 1 and FIG. 2, in a packing bag of the present invention composed of a rectangular sheet piece 1 of synthetic resin, the sheet piece 1 is folded on two convex folded line portions 18 and one concave folded line portion 19, and a folded portion 10, M-shaped in longitudinal cross section and serially having a first sheet layer 11, a second sheet layer 12, a third sheet layer 13, and a fourth sheet layer 14, is formed on an end edge portion 1A.

In a state that the folded portion 10 is formed on the end edge portion 1A, both of left and right end edge portions 1B of the sheet piece 1 are welded, and an opening portion 3 to put a packed article Z is formed on another end edge portion 1C.

Polyolefin resins such as polyethylene and polypropylene can be used as the material for the sheet piece 1. PET resin or nylon may also be used as the material. The opening portion 3 is closed by welding after the entrance of the packed article Z. The packed article Z is one of articles such as food, medicine, supplement, pet food, cosmetics, or sundries. In the present invention, “welding” is a work in which resins are mutually connected by heat and pressing force without adhesives, and also expressed as “heat press fitting” or “heat welding”.

The first sheet layer 11 and the second sheet layer are welded on the folded portion 10, and, the third sheet layer 13 and the fourth sheet layer 14 are welded on the folded portion 10. And, a separation-prepared line portion 5, with which the second sheet layer 12 and the third sheet layer 13 can be separated, is formed along the concave folded line portion 19 between the second sheet layer 12 and the third sheet layer 13.

A welded portion 15 of thin belt shape in left-and-right direction is formed by welding the first sheet layer and the second sheet layer 12 near the concave folded line portion 19. And, a welded portion 15 of thin belt shape in left-and-right direction is formed by welding the third sheet layer 13 and the fourth sheet layer 14 near the concave folded line portion 19.

The separation-prepared line portion 5 is easier to break than other parts of the sheet piece 1 for a V-shaped groove, of which depth dimension is ⅓ of the thickness dimension of the sheet piece 1, is formed straight along the concave folded line portion 19. It is also preferable to form a half-cut line or perforation line as the separation-prepared line portion 5. The separation-prepared line portion 5, not restricted to straight shape, may be a wave or zigzag line.

A fastener 4, which can tightly seal the second sheet layer 12 and the third sheet layer 13 mutually, is provided, and the separation-prepared line portion 5 is disposed on an inner side of the bag against the fastener 4.

The fastener 4 is composed of a chuck tape male portion 4A having a convex portion and a chuck tape female portion 4B having a concave portion to which the convex portion fits, and the chuck tape male portion 4A and the chuck tape female portion 4B are welded to inner face near the convex folded line portions 18 of the second sheet layer 12 and the third sheet layer 13 as to make the convex portion and the concave portion facing. With the fastener 4, the convex portion and the concave portion can be fit by holding the outer face of the folded portion 10 (the first sheet layer 11 and the fourth sheet layer 14) by fingers to mutually press the chuck tape male portion 4A and the chuck tape female portion 4B, and the second sheet layer 12 and the third sheet layer 13 are connected to close the bag. On the contrary, the fitting of the convex portion and the concave portion is released by holding and pulling near the convex folded line portion 18 of the first sheet layer 11 and the second sheet layer 12 and near the convex folded line portion 18 of the third sheet layer 13 and the fourth sheet layer 14 by fingers to open the fastener 4.

A method of use (function) of the above-described packing bag of the present invention is described.

As in FIG. 1, the packed article Z is put into the opening portion 3 and stored in the packing bag in which the folded portion 10 is formed on the end edge portion 1A and the left and right end edge portions 1B are welded, and the end edge portion 1C is welded to make a sealed state before opening. In the sealed state before opening, the stored packed article Z is kept from humidity or prevented from being dried to be protected with sanitation.

As shown in FIG. 2 and FIG. 3, the fastener 4 is opened, and the second sheet layer 12 and the third sheet layer 13 are widely opened. The fastener 4 can be easily opened keeping sufficient strength on the peripheral end edge portion forming the convex folded line portions 18 because the first sheet layer 11 and the second sheet layer 12 are layered and welded, and the third sheet layer 13 and the fourth sheet layer 14 are layered and welded.

As shown in FIG. 4, when tensile force F is given further in the directions to open the second sheet layer 12 and the third sheet layer 13, the second sheet layer 12 and the third sheet layer 13 are separated along the separation-prepared line portion 5 (the convex folded line portion 18) to be opened, and the packed article Z can be taken out. The packed article Z can be prevented from intruding between the first sheet layer 11 and the second sheet layer 12 and between the third sheet layer 13 and the fourth sheet layer 14 when taken out, and the packed article Z does not hitch to the second sheet layer 12 and the third sheet layer 13 and does not make the takeout difficult because the first sheet layer 11 and the second sheet layer 12 are welded (on the welded portion 15 near the separation-prepared line portion 5), and the third sheet layer 13 and the fourth sheet layer 14 are welded (on the welded portion 15 near the separation-prepared line portion 5). Once opened, although air-tightness is not higher than before the opening, quasi-tight sealed state can be made by closing the fastener 4.

Next, another embodiment of the present invention is described.

As shown in FIG. 5 and FIG. 6, a slider 8 is attached to the folded portion 10 to open and close the fastener 4.

The slider 8 is composed of two plastic parts one of which plays a role of opening the fastener 4, and the other of which plays a role of closing the fastener 4. The slider 8, with a construction in which the two parts are combined, is composed as to be easily attached to the fastener 4. In FIG. 5 and FIG. 6, the slider 8 is not influenced before the opening because the separation-prepared line portion 5 is disposed on the inner side of the bag against the fastener 4. For example, in conventional packing bags, the slider can't be provided or the slider is attached after the opening because a part of the peripheral edge portion is cut off. In case that the slider is attached later, the cut face of the peripheral edge portion is uneven (not straight), and it is difficult to smoothly run the slider. On the contrary, according to the present invention, the slider 8 can be attached to the folded portion 10 before the opening, and the fastener 4 can be easily opened and closed by the slider 8 both of before and after the opening.

In FIG. 5 and FIG. 6, the fastener 4 is attached to a position nearer to the convex folded line portions 18 of the second sheet layer 12 and the third sheet layer 13. The other constructions are similar to that of above-described embodiment in FIG. 1.

In FIG. 7, another embodiment of the present invention is shown.

In FIG. 7, a through hole 9 for suspension is formed on the folded portion 10.

The through hole 9 is a round hole penetrating the first sheet layer 11, the second sheet layer 12, the third sheet layer 13, and the fourth sheet layer 14, and disposed on a position upper to the fastener 4 (a position near the convex folded line portion 18). The folded portion 10 keeps sufficient strength for the layering of the 4 layers 11, 12, 13, and 14, the folded portion 10 can support a load without deformation when suspended by a hook inserted to the through hole 9, and the bag is appropriate for suspended display. And, the bag can be suspended by the hook inserted to the through hole 9 even after the opening, and foods and medicines are easily stored with sanitation.

Next, a production method of the packing bag of the present invention is described.

As shown in FIG. 8(A), in a first process, sheet material in rolled state is continuously fed, and, the chuck tape male portion 4A and the chuck tape female portion 4B are disposed parallel on a face 31 a of the sheet material 31 along a longitudinal direction to fuse.

The long chuck tape male portion 4A and the chuck tape female portion 4B (refer to FIG. 8(B)) being continuously sent, are inserted between (the face 31 a of) the sheet material 31 and a drum 40. Plural concave grooves 41 corresponding at least to the chuck tape male portion 4A and the chuck tape female portion 4B are disposed on the drum 40, the chuck tape male portion 4A and the chuck tape female portion 4B are fit to the concave grooves 41, and the chuck tape male portion 4A and the chuck tape female portion 4B are welded to the face 31 a of the sheet material 31 by heating.

In a preliminary process of the first process (process 0), at least one of letters, figures, signs, patterns, colors is printed on the face 31 a of the sheet material 31.

As shown in FIG. 8(C), the sheet material 31 has a three-layer construction having a middle layer 24 composed of synthetic resin of polyamide system or PET resin, and protection layers 25 composed of PP (CPP) or PE covering the obverse and reverse sides of the middle layer 24. Ink 26 showing letters, figures, signs, patterns, colors, etc. exists between the middle layer 24 and the protection layer 25 on the face 31 a side. The protection layer 25 may be colored to express patterns and colors. And, although not shown in figures, the sheet material 31 may have a two-layer construction in which the protection layer 25 is only on the face 31 a side of the middle layer 24 and the protection layer 25 on the other face 31 b side is omitted.

As shown in FIG. 8 and FIG. 9, in a second process, the separation-prepared line portion 5 of concave groove is formed on a center line in width direction between the chuck tape male portion 4A and the chuck tape female portion 4B by a heated blade 29 from the face 31 a side of the sheet material 31.

The separation-prepared line portion 5 is preferably formed with a depth dimension of 30 to 60% of the thickness dimension of the sheet material 31 as to break easier than other parts of the sheet material 31. The order of the first process and the second process may be interchanged, namely, the process of forming the separation-prepared line portion 5 on the sheet material 31 may be the first process, and the process of fusing the chuck tape male portion 4A and the chuck tape female portion 4B to the face 31 a of the sheet material 31 may be the second process. And, although not shown in figures, the separation-prepared line portion 5 may be formed from the other face 31 b side of the sheet material 31.

Next, as shown in FIG. 10, in a third process, the sheet material 31 is folded along the separation-prepared line portion 5 as the face 31 a is directed outward to form a fold back portion 27.

In FIG. 10, the sheet material 31 is continuously sent and made sliding on the triangular guiding plate 33, and the sheet material 31 is folded back on the fold back portion 27 as shown in FIG. 11 and FIG. 12. In this case, the separation-prepared line portion 5 is disposed on the outside of the fold back portion 27, and the convex portion of the chuck tape male portion 4A and the concave portion of the chuck tape female portion 4B are directed to mutually opposite directions.

Then, as shown in FIG. 13 and FIG. 14, in a fourth process, a guiding roller 36 for reverse folding is applied from the face 31 a side of the fold back portion 27 of the sheet material 31, a pair of reverse fold guiding members 37, to which the guiding roller 36 is inserted, is applied from the other face 31 b of the sheet material 31, and the sheet material 31 is folded along the two convex folded line portions 18 and the concave folded line portion 19 to form the folded portion (fold-up portion) 10 of which cross section is M-shaped.

The sheet material 31 after the fourth process, as shown in FIG. 15, is composed of the first sheet layer 11, the second sheet layer 12, the third sheet layer 13, and the fourth sheet layer 14 serially layered. The depth dimension L from the convex folded line portions 18 to the concave folded line portion 19 of the folded portion 10 can be freely changed by an adjustment means 32 (refer to FIG. 13) to adjust the insertion depth of the guiding roller 36 and the reverse fold guiding members 37.

In FIG. 15, the chuck tape male portion 4A and the chuck tape female portion 4B are facing to be fit to form the fastener 4 which can seal the second sheet layer and the third sheet layer 13 each other. And, the separation-prepared line portion 5 is disposed on the inner side of the bag to the fastener 4 (along the concave folded line portion 19). After the folded portion 10 is formed, the sheet material 31 in continuous feeding is switched to intermittent feeding by a feeding speed regulating device (not shown in figures).

Next, as shown in FIG. 16 and FIG. 17, in a fifth process, while the sheet material 31 is intermittently fed, the first sheet layer 11 and the second sheet layer 12 are mutually welded, and the third sheet layer 13 and the fourth sheet layer 14 are mutually welded.

In FIG. 17, an interval keeping member 23 is inserted between the second sheet layer 12 and the third sheet layer 13 of the folded portion 10, the first sheet layer 11 and the second sheet layer 12 are mutually welded, and the third sheet layer 13 and the fourth sheet layer 14 are mutually welded by giving heat and pressing force of heat welding members 34 press-fit to the first sheet layer and the fourth sheet layer 14 on the upper and lower sides of the folded portion 10. The welded portion 15 of the first sheet layer 11 and the second sheet layer 12 and the welded portion 15 of the third sheet layer 13 and the fourth sheet layer 14 are continuously formed belt-shaped along the longitudinal direction of the sheet material 31, and the welded portion 15 is formed near the concave folded line portion 19 as to make the distance between the lower end edge of the welded portion 15 and the concave folded line portion 19 shorter than the width of the welded portion 15.

Next, as shown in FIG. 18, in a sixth process, welded portions 28 in width direction are serially formed with predetermined pitch for the entire length in width direction of the sheet material 31, and the sheet material 31 is cut on a center position of the welded portion 28 in width direction.

And, in case that the slider 8 to open and close the fastener 4 is attached to the folded portion 10, the two plastic parts are assembled to form the slider 8 in a seventh process shown in FIG. 19. The slider 8 is easily attached to the folded portion 10 for the construction in which the two parts are combined. The welding may be conducted simultaneously with the cutting (“fuse cutting” may be used).

In the packing bag produced by the production process shown in FIG. 8 through FIG. 19, as shown in FIG. 1 or FIG. 5, the sheet material 31 (the sheet piece 1), of which thickness dimension is made uniform, is folded on the two convex folded line portions 18 and the concave folded line portion 19 to form the folded portion serially having the first sheet layer 11, the second sheet layer 12, the third sheet layer 13, and the fourth sheet layer 14 on the end edge portion 1A to form M-shape in longitudinal cross section. The belt-shaped welded portion 15 is formed for the entire width of the bag by mutual connection and heat welding of the first sheet layer 11 and the second sheet layer 12 of the folded portion 10 by adding heat and pressing force, the belt-shaped welded portion 15 is formed for the entire width of the bag by mutual connection and heat welding of the third sheet layer 13 and the fourth sheet layer 14 of the folded portion 10 by adding heat and pressing force, further, the separation-prepared line portion 5, with which the second sheet layer 12 and the third sheet layer 13 can be separated along the concave folded line portion 19 between the second sheet layer 12 and the third sheet layer 13, is formed, the fastener 4 to mutually seal the second sheet layer 12 and the third sheet layer 13 is provided, and the separation-prepared line portion 5 is disposed on the inner side of the bag to the fastener 4.

The chuck tape male portion 4A and the chuck tape female portion 4B (the fastener 4) are welded to the inner faces of the second sheet layer 12 and the third sheet layer 13 near the convex folded line portions 18, the first sheet layer 11 and the second sheet layer 12 are welded on a position other than the chuck tape male portion 4A near the concave folded line portion 19 to form the welded portion 15, and the third sheet layer 13 and the fourth sheet layer 14 are welded on a position other than the chuck tape female portion 4B near the concave folded line portion 19 to form the welded portion 15. The welded portions 15 are formed thin belt-shaped for the entire length of the left-right direction (width direction) of the packing bag. The both end edge portions 1B of the packing bag are welded for the entire length, and an end portion of the end edge portion 1B forms a stopper to prevent departure of the slider 8.

As shown in FIG. 20, when the fastener 4 is opened to open the bag by releasing the fitting of the chuck tape male portion 4A and the chuck tape female portion 4B, two points on the convex folded line portions 18 are pulled by fingers to break the separation-prepared line portion 5 to separate the second sheet layer 12 and the third sheet layer 13.

In the production process in which the face 31 a of the sheet material 31 is printed, an indicating portion 16 to indicate the breaking of the separation-prepared line portion 5 is provided on a belt-shaped area supposed to form the concave folded line portion 19 of the folded portion 10. The indicating portion 16, concretely, is composed of an arrow indicating the separation-prepared line portion 5 and a phrase “Break here!”. The indicating portion 16, not restricted to the example, the letters and the sign may be changed, and other letters, figures, signs, patterns, and colors may be added. The belt-shaped area supposed to form the concave folded line portion 19 is a part of or entire belt-shaped area between the chuck tape male portion 4A and the chuck tape female portion 4B of the face 31 a of the sheet material 31, and, in other words, a part of or entire inner faces of the second sheet layer 12 and the third sheet layer 13.

As shown in FIG. 21, the sheet material 31 (in rolled state) is preliminarily printed with letters and signs only on the face 31 a, and the inner side of the folded portion 10 (the inner faces of the second sheet layer 12 and the third sheet layer 13) can be made the printed face by folding the sheet material 31. That is to say, printing on the both sides of the sheet material 31 is not necessary, the printing can be easily conducted only on the face 31 a with low cost, further, the indicating portion is easily provided on the inner side of the folded portion 10.

Next, another production method is described.

As shown in FIG. 22, after the forming of the folded portion 10 on the sheet material 31, the sheet material 31 is intermittently fed, the first sheet layer 11 and the second sheet layer 12 are mutually welded and the third sheet layer 13 and the fourth sheet layer 14 are mutually welded by giving heat and pressing force by heat welding members 42 of which cross section is U-shaped on the upper and lower sides of the folded portion 10. In FIG. 22, the first sheet layer 11 and the second sheet layer 12 are mutually welded on a welded portion 38 near the concave folded line portion 19 and a welded portion 39 near the convex folded line portion 18, and, the third sheet layer 13 and the fourth sheet layer 14 are mutually welded on the welded portion 38 near the concave folded line portion 19 and the welded portion 39 near the convex folded line portion 18. The chuck tape male portion 4A and the chuck tape female portion 4B are disposed slightly inner side of the bag to the lower end edge of the welded portion 39 near the convex folded line portion 18.

Then, welded portions 43 in width direction are serially formed with a predetermined pitch for the entire length in the width dimension of the sheet material 31, and a through hole 45 is formed on the welded portion 39 near the convex folded line portion 18 by a punch means 44. And, the sheet material 31 is cut on a center position of the welded portion 43 in width direction by a cutting means 46. The packing bag produced by the production process in FIG. 22 is provided with the through hole 45 for suspension on the folded portion 10 as shown in FIG. 23.

As shown in FIG. 24 and FIG. 25, two lines of packing bags may be taken from one sheet material 31.

In FIG. 24, the sheet material 31, of which face 31 a is preliminarily printed with letters and signs, is continuously fed, two pairs of the chuck tape male portions 4A and the chuck tape female portions 4B are welded to the face 31 a of the sheet material 31 with a predetermined interval in width direction. The plural concave grooves 41 are formed on the drum 40 as to correspond to the attached positions of the chuck tape male portions 4A and the chuck tape female portions 4B, and, the chuck tape male portions 4A and the chuck tape female portions 4B are inserted to the concave grooves 41 to be welded to the face 31 a of the sheet material 31.

Next, the separation-prepared line portion 5 of concave groove is formed on each of center lines in width direction of the chuck tape male portions 4A and the chuck tape female portions 4B by the heated blade 29 on the face 31 a side and the face 31 b side of the sheet material 31. That is to say, two separation⁻prepared line portions 5 are formed on the sheet material 31.

In FIG. 25, the sheet material 31 is folded along the two separation-prepared line portions 5 as the face 31 a is directed outward to form the fold back portions 27 on the both end edge portions in width direction, then, the guiding roller 36 for reverse folding is applied to each of the fold back portions 27 from the face 31 a side, a pair of the reverse fold guiding members 37, disposed to insert the guiding roller 36, is applied to each of the fold back portions 27 from the face 31 b side of the sheet material 31, each of the both end edge portions in width direction is folded along the two convex folded line portions 18 and the concave folded line portion 19 to form the folded portions 10 of which cross section is M-shaped on two positions on the sheet material 31. And, the sheet material 31 is cut by a cutting blade 50 along the center line in width direction. Production efficiency can be improved twice thereby.

In the present invention, being modifiable, the slider 8, for example, is not restricted to the above-described construction and may be changed.

With the construction described above, the welded portions 15 can be formed without increasing the thickness dimension near the concave folded line portion 19 of the folded portion 10, and the packed article Z can be prevented from intruding between the first sheet layer 11 and the second sheet layer 12 and between the third sheet layer 13 and the fourth sheet layer 14 when taken out. The packed article Z can be easily taken out without hitching to the separated second sheet layer 12 and the third sheet layer 13. In the production process, the fastener 4 can be efficiently and beautifully attached with high quality by welding of the chuck tape male portions 4A and the chuck tape female portions 4B to the obverse face (the face 31 a) of the sheet material 31. The process of welding of the chuck tape male portions 4A and the chuck tape female portions 4B to the sheet piece 1 and the process of forming the welded portions 15 on the folded portion 10 can be separately conducted, and the fastener 4 can be beautifully attached with high quality only on the second sheet layer 12 and the third sheet layer 13. Further, the first sheet layer 11 and the second sheet layer 12 can be certainly welded by heat welding, and, the third sheet layer 13 and the fourth sheet layer 14 can be certainly welded by heat welding on the welded portions 15.

As described above, the bag can be opened by breaking the sheet piece 1 on the separation-prepared line portion 5 without cutting the peripheral edge portion, and used in good appearance after the opening because the packing bag of the present invention is composed of the rectangular sheet piece 1 of synthetic resin, the sheet piece 1 is folded on the two convex folded line portions 18 and the concave folded line portion 19 to form the folded portion 10 serially having the first sheet layer 11, the second sheet layer 12, the third sheet layer 13, and the fourth sheet layer 14 on the end edge portion 1A to form M-shape in longitudinal cross section, the first sheet layer and the second sheet layer 2 are fused, and the third sheet layer 3 and the fourth sheet layer 4 are fused, the separation-prepared line portion 5 to separate the second sheet layer 2 and the third sheet layer 3 along the concave folded line portion 19 between the second sheet layer 2 and the third sheet layer 3, the fastener 4 to mutually seal the second sheet layer 2 and the third sheet layer 3, and, the separation-prepared line portion 5 is disposed on the inner side of the bag to the fastener 4. And, refuse is not generated because the bag can be opened not cutting the peripheral edge portion. In the production process, feeding the sheet piece 1 (the sheet material 31) in rolled state continuously, the fastener 4 can be efficiently and beautifully attached to the obverse face (the face 31 a) of the sheet piece 1 (the sheet material 31) by welding with high quality. The separation-prepared line portion 5 can be beautifully formed with high accuracy to improve working efficiency in production. The folded portion 10, forming M-shape in longitudinal cross section, can be formed thin keeping strength and proper rigidity for the first sheet layer 11, the second sheet layer 12, the third sheet layer 13, and the fourth sheet layer 14 of uniform thickness dimension. The thickness dimension and size of the sheet piece 1 is easily changed to flexibly correspond to various kinds and sizes. The bag can be economically produced in spite of the construction with the fastener 4. The sheet piece 1 in rolled state can be continuously printed.

And, the welding work of the opening portion 3, after the packed article Z is inserted through the opening portion 3 and stored, can be made automatic to improve working efficiency because the left and right both end edge portions 1B of the sheet piece 1 are welded in the state that the folded portion 10 is formed on the end edge portion 1A, and the opening portion 3 to put the packed article Z in the bag is formed on another end edge portion 1G. The left and right both end edge portions 1B on the folded portion 10 can be beautifully welded with high quality.

And, the slider 8 can be attached to the folded portion 10 before opening, and the fastener 4 can be easily opened and closed before and after the opening because the slider 8 is attached to the folded portion 10 to open and close the fastener 4.

And, the folded portion 10 can keep sufficient strength and support the load without deformation when suspended by the hook inserted to the through hole 9, and the bag is appropriate for suspended display because the through hole 9 for suspension is formed on the folded portion 10. The bag can be suspended by the hook inserted to the through hole 9 after the opening, and stored in small space with sanitation.

EXPLANATION OF THE MARKS

-   1 A sheet piece -   1A An end edge portion -   1B left and right both end edge portions -   3 An opening portion -   4 A fastener -   5 A separation-prepared line portion -   8 A slider -   9 A through hole -   10 A folded portion -   11 A first sheet layer -   12 A second sheet layer -   13 A third sheet layer -   14 A fourth sheet layer -   18 A convex folded line portion -   19 A concave folded line portion -   Z A packed article 

1. A packing bag composed of a rectangular sheet piece (1) of synthetic resin characterized by that: the sheet piece (1) is folded on two convex folded line portions (18) and a concave folded line portion (19) to form a folded portion (10) serially having a first sheet layer (11), a second sheet layer (12), a third sheet layer (13), and a fourth sheet layer (14) on an end edge portion (1A) to form M-shape in longitudinal cross section; the first sheet layer (1) and the second sheet layer (2) are fused, and the third sheet layer (3) and the fourth sheet layer (4) are fused; a separation-prepared line portion (5) to separate the second sheet layer (2) and the third sheet layer (3) is formed along the concave folded line portion (19) between the second sheet layer (2) and the third sheet layer (3); a fastener (4) to mutually seal the second sheet layer (2) and the third sheet layer (3) is provided; and the separation-prepared line portion (5) is disposed on an inner side of the bag to the fastener (4).
 2. The packing bag as set forth in claim 1, wherein left and right both end edge portions (1B) of the sheet piece (1) are welded in a state that the folded portion (10) is formed on the end edge portion (1A), and an opening portion (3) to put a packed article (Z) in the bag is formed on another end edge portion (1C).
 3. The packing bag as set forth in claim 1, wherein a slider (8) is attached to the folded portion (10) to open and close the fastener (4).
 4. The packing bag as set forth in claim 1, wherein a through hole (9) for suspension is formed on the folded portion (10).
 5. The packing bag as set forth in claim 2, wherein a slider (8) is attached to the folded portion (10) to open and close the fastener (4).
 6. The packing bag as set forth in claim 2, wherein a through hole (9) for suspension is formed on the folded portion (10). 